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Transfer Case Spotter’s Guide

One person’s trash is often someone else’s treasure. With this in mind, we are profiling a few enthusiast-worthy OE transfer cases from U.S.-brand applications. It will hopefully help narrow down low-range shopping in the classifieds or in the junkyard.

New Process/New Venture transfer cases are easy to identify. Early models have a rectangular ID plate screwed to the back of the case; newer ones have a round red/silver/black tag on their backsides. BorgWarner models have an assembly tag secured by one of the housing’s bolts.

The accompanying chart gives an overview of most Detroit Three transfer cases. Listed dates are sometimes manufacturing years as opposed to vehicle model years. Also, all transfer case models can have several variations depending on application and year. All listings are part-time and chain-drive/aluminum-case unless otherwise noted.

Dana/Spicer Model 20Identify: Single shifter; same casting as the later Model 18; rear output is centered. Low-Ranges: 2.0, 2.34, 2.46Lubricant: 85W-90 gear oilNotes: Versions also appeared in Jeep, IH, Ford, and Chevy 4x4s. Some parts are interchangeable among versions. The ’66-’72 Bronco had the T-shift with 2.46 low-range; ’73-’77 vehicles had the 2.34-geared J-shift variant. The Bronco Model 20’s sliding gear can be combined with Model 18 gears to create a 2.46 low-range in Jeep and IH Model 20s.

BW 1305/BW 1339Identify: Outputs offset to the passenger side; the aluminum case is split laterally; 1339 models (shown) have a gear-reduction box.Low-Range: 2.57 (BW 1339)Lubricant: Special fluidNotes: Unveiled in the ’73 Wagoneer, the Quadra-Trac BW 1305 was the first mass-production chain-drive/aluminum-housing transfer case. This full-time unit didn’t have a low-range. The BW 1339 version added a planetary gearbox to produce a low-range. This transfer case has an internal differential, which can be locked by a glovebox-mounted vacuum switch to split torque evenly front to rear. Rebuild parts are rare, although MileMarker offers a part-time conversion kit and an overdrive chain. The Model 18 is a direct replacement.

BW 1356FIdentify: Ribbed magnesium case, long aluminum tailshaft housingLow-Range: 2.69Lubricant: ATFNotes: The 1356 replaced the 1345 in the 1987 Bronco. It was in the Bronco through 1996 and in F-Series trucks and motorhome chasses from 1988 to 1991. Manual (pre-1992) and electric shift versions were made.

NP208Identify: Aluminum case; driver-side front output.Low-Range: 2.62Lubricant: ATFNotes: It looks similar to the NP207 but has a 23-spline input shaft. Found in ’80s Cherokees and pickups, it is the heart of the Command-Trac system. Dodge and Jeep versions have bolt-on yokes; others have a slip-yoke.

NP203Identify: Cast-iron housingLow-Range: 1.96Lubricant: 85W-90 gear oilNotes: Many of these full-time transfer cases have been converted to part-time with manually locking front hubs using a Doug Nash-designed kit, now sold by MileMarker. Depending on OE application, input spline counts are 10, 28, and 32.

NP205Identify: Aluminum output and input retainers; front output can be offset to either passenger or driver side; rear center output; rear cover is round and has three bolts; a divorced version has a yoke on the input; some have a rear slip yokeLow-Range: 1.96Lubricant: 85W-90 or heavier gear oil.Notes: The king of heavy-weight light-duty transfer cases, its main compromise is low-range gearing. Aftermarket upgrades include lower-gear gearsets and piggybacks as well as twin sticks. Each U.S. manufacturer, including IH, used the NP205 at some point, and six different input/output versions exist.

NP/NV 241Identify: 6-bolt front face. Front output is either on the driver side (IFS) or passenger side (solid axle). Early speed sensors are mechanical, later are electronic.Lubricant: ATFLow-Range: 2.72Notes: The 241OR Rock-Trac version (shown) in the Wrangler Rubicon is revered for its 4.0 low-range and fixed output yoke with electronic speed sensor. The housing has more ribs than the NP241D found in Dodge trucks. The Dodge version also has a long slip yoke housing. Input shaft spline counts vary depending on duty rating: 23, 27, 29, 31 and 32. The Dodge/Ram 1⁄2- and 3⁄4-ton version is designated 241DLD; the 241DHD 1-ton model includes a PTO output.

NP 207Identify: Aluminum case, driver-side front output.Low-Range: 2.60Lubricant: ATFNotes: One of the weaker Jeep transfer cases, it was in ’84-’87 XJs and the ’87 YJ.

NP/NV 242Identify: 6-bolt front face; longitudinally ribbed case; rear outputs can be either fixed or slip-yoke.Lubricant: ATFLow-Range: 2.72Notes: This transfer case offers a driver-selectable full-time mode, which splits front/rear torque 48/52 percent. It also has “normal” 4-Hi and 4-Lo. The Hummer version has stronger 32-spline shafts, a 6-pinion differential, a wider chain, and a cooler. Jeeps (shown) have 21- and 23-spline input shafts, depending on OE transmission. The 242 is durable, and replacement parts are plentiful.

NP/NV 231Identify: Driver-side front output; centered rear output; 6-bolt front face on Jeep and Dodge, and 5-bolt front face on GM.Low-Range: 2.72Lubricant: ATFNotes: One of the most popular transfer cases, a 231 version appears in many recent GM and Chrysler/Jeep 1⁄2-ton applications (231J shown). Early models use a cable-driven speedometer. Electric speed sensors appeared in 1992. GM 231C models can be adapted to Jeeps if many parts are mixed and interchanged. Jeep versions (14 configurations were made) have varying input gears depending on their OE transmissions. Also, non-TJ models have a slip yoke, which enthusiasts often convert to a fixed yoke. The heavier-duty 231HD appears in the ZJ Grand Cherokee, and the 231HDD is in Ram 1500s (12 Dodge versions were built). Many replacement and upgraded parts are available.

NV 271/NV 273Identify: Magnesium caseLow-Range: 2.72Lubricant: ATFNotes: Basically the same case, the 271 has a manual shifter and the 273 (shown) is electronically shifted; found in Ram and Ford HD trucks.